This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The long-term objectives of this proposal are to clarify the role of microRNAs and their target genes during mammalian orofacial development. Formation of the mammalian orofacial tissue is a complex, coordinated developmental process involving cell migration, proliferation, differentiation, apoptosis, and synthesis of extracellular matrix. All these critical cellular processes are believed to be under the control of numerous microRNAs (miRNAs) and their target genes encoding growth and differentiation factors, signaling mediators, transcription factors and extracellular matrix proteins. Disruptions in any one of these processes can lead to orofacial clefting. Emerging evidences strongly support central roles for miRNAs in orofacial ontogenesis. Our preliminary data demonstrated that a panoply of miRNA- and protein-coding genes are differentially expressed during the crucial period of orofacial development. Bioinformatic analysis revealed identification of several target genes (of those miRNAs) many of which have documented critical roles in orofacial morphogenesis. Furthermore, pathway analysis enabled identification of important biological pathways or gene interaction networks involving the miRNAs and their target genes, as well as linking vital cellular processes governing growth of the embryonic orofacial region. We thus propose to test the hypothesis that interaction between differentially-expressed miRNAs and their target mRNAs are essential for proper development of the embryonic orofacial region. Three hypothesis-driven specific aims will be pursued: 1) Within the developing orofacial tissue several differentially expressed genes encoding mRNAs are targets of miRNAs differentially expressed in that tissue. 2) Interaction between differentially-expressed miRNAs and mRNAs are essential for the regulation of specific biological processes as well as phenotypic outcomes associated with orofacial development. 3) Overexpression or inhibition of expression of discrete miRNAs modulates the expression of their target genes which in turn affects the cellular processes indispensable for the morphogenesis of the orofacial region.